The present invention relates generally to a vascular catheter and insertion needle assembly and, more specifically, to an assembly that includes a tip protector that safely shields the insertion needle tip when withdrawn from the catheter.
Catheters are well known for being used to fluidly communicate with the vascular system of a patient in a minimally invasive procedure, whether to withdraw fluids from the patient or to infuse fluids into the patient. Catheters are generally short thin flexible tubes that are open at a distal end and secured within a hub at a proximal end. The hub serves as a quick disconnectable mechanical connector between the catheter and a delivery tube extending, for example, from a liquid source.
One typical catheter is an over-the needle style catheter that requires an insertion needle passing therethrough to penetrate the patient""s skin and advance the catheter into the patient""s vascular system. The needle comprises a beveled distal end to facilitate piercing the patient""s skin and a proximal end having a hub for handling purposes. When the distal end of the catheter is in place within the patient""s vascular system, the insertion needle may be withdrawn, leaving the catheter hub exposed at the proximal end to connect to a delivery tube. Pressure applied by the clinician to the blood vessel occludes blood flow, permitting the clinician to connect the catheter hub to the delivery tube either to withdraw blood or to infuse fluids into the patient.
Traditionally, once the insertion needle was withdrawn from the catheter, the sharp distal tip of the needle was left exposed to the clinician until properly disposed. This put the clinician at risk of being inadvertently xe2x80x9cstuckxe2x80x9d by the needle, causing injury and, more critically, to inadvertent internal exposure to the patient""s blood. Where a patient suffers from a communicable disease, particularly Acquired Immunosuppressive Deficiency Syndrome (AIDS), that risk is unacceptable. Despite being aware of the need to properly handle blood contaminated needles, under certain circumstances, including emergency situations or inattention, inadvertent sticks of the insertion needle into the clinician still occur.
To address the problem, efforts have been made to shield the exposed tip of the needle when it is withdrawn from the patient. For example, U.S. Pat. No. 6,004,294 to Brimhall et al. discloses a needle shield that includes a leaf spring that engages a shoulder formed from a tapered section of the insertion needle to prevent axial movement of the insertion needle after it has been withdrawn to a certain position. While effective at shielding the needle tip, the Brimhall device is a somewhat complex arrangement of features that results in a more expensive and cumbersome assembly that can be misused. A simpler passive and more efficient tip protecting assembly is desired.
The present invention is a catheter and insertion needle assembly that overcomes the deficiencies of the prior art by providing a simpler, entirely passive, and more effective means for safely shielding the distal tip of the insertion needle as it is withdrawn from the catheter. The result is that the clinician may use the assembly without risk of inadvertent injuries and, more importantly, without risk of contracting a communicable disease from the patient undergoing treatment. The present invention is a catheter and insertion needle assembly that comprises a catheter with catheter hub, an insertion needle, means for shielding the tip of the needle, means for locking the needle within the shielding means and means for removably locking the shielding means within the catheter hub. Specifically, the preferred embodiment of the assembly comprises a soft resilient catheter that has preferably been treated at its distal end to create a relatively hard catheter tip for facilitating engagement with a patient, as described in co-pending applications, Ser. No. 09/146,451, now U.S. Pat. No. 6,500,157, and Ser. No. 09/524,039, entitled Hard Tip Over-The-Needle Intravenous Catheter and filed on Mar. 13, 2000, which are incorporated herein in their entirety by reference. The catheter further preferably includes an internal shoulder near the distal end thereof that may be provided by the techniques described in the referenced application.
The shielding means comprises a shield or tip protector comprising a generally cylindrical tube configured so as to be disconnectably disposed within the catheter hub. The tip protector preferably includes a retainer ring externally positioned thereon, wherein the retainer ring is configured to engage a corresponding retainer depression in an internal wall of the catheter hub. When the retainer ring is engaged with the retainer depression, the tip protector remains securely positioned within the catheter hub. When the retainer ring is not engaged with the retainer depression, the tip protector may be moved axially within the catheter hub. The proximal end of the tip protector has a small opening that is just large enough to permit the passage of the insertion needle through but small enough to preclude passage of the locking ring. The distal end has an internal diameter sufficiently large to permit passage of both the needle and the locking ring.
The insertion needle comprises a uniform diameter cannula that has a beveled tip at its distal end. The needle is sized to be axially disposed within the catheter and catheter hub. The means for locking the needle tip within the tip protector comprises in part a locking ring securely disposed over the needle near the distal end of the needle. The locking ring is positioned on the needle so as to permit the needle tip to project through the catheter sufficiently to provide effective penetration of the needle and catheter into a patient""s vascular system. The locking ring is also preferably positioned on the needle so as to abut the internal shoulder of the catheter when the insertion needle is fully inserted within the catheter.
The means for locking the needle tip within the tip protector further comprises an insert comprising a short, generally cylindrical, metal, collar disposed securely within the interior of the tip protector. The insert is intended to be immovable within the tip protector. The insert has a slight decreasing taper at its proximal end so that the interior diameter of the proximal end is large enough to permit the passage therethrough of the insertion needle but small enough to preclude easy passage of the locking ring, although it may be forced through, as explained below. The tapered end of insert is segmented into discrete cantilevered sections that may be biased outwardly when the locking ring is forced through the insert. It is intended that the metal insert be positioned within the tip protector so that, when the insertion needle and locking ring are withdrawn proximally and forcibly through the insert, the locking ring is restricted from further axial movement in either direction between the metal insert and the proximal end of the tip protector.
With the above arrangement, when the insertion needle is inserted within the catheter to its fullest extent, the locking ring abuts the internal shoulder of the catheter. The abutment helps to transfer forces from the needle to the catheter as the needle is pushed distally through the catheter and into the patient. The hard tip helps to advance the otherwise soft catheter into the patient""s vascular system. When the insertion needle is withdrawn from the patient, it moves axially through the tip protector so that the locking ring forcibly passes through the spring actuating metal insert. The locking ring then becomes lodged between the metal insert and the proximal end of the tip protector, preventing further axially movement of the needle within the tip protector. At this point, the insertion needle is, in effect, locked in place. By exerting additional pulling force on the insertion needle in the proximal direction, the pressure of the locking ring against the proximal end of the tip protector forces the tip protector to disengage from the catheter hub. Continued pulling results in the insertion needle being fully withdrawn from the catheter and catheter hub with the distal tip of the insertion needle securely shielded by the tip protector against inadvertent sticks by clinicians.